A multi-cylinder engine is available wherein a plurality of cylinders are divided into at least two groups and are each formed from cylinders each of which can be cut off (i.e., turned off) by placing a throttle valve thereof into a closed state using a link or a rod such that the number of operating cylinders can be adjusted in response to the engine load. For an example refer to JP 07-150982.
Also another multi-cylinder engine is available wherein a cylinder cut-off mechanism provided for an engine valve is operated hydraulically without a link or a rod to place the engine valve into a closed state. For an example refer to JP 2000-205038 (U.S. Pat. No. 6,318,316).
In the former multi-cylinder engine, the link or rod restricts the degree of freedom of the arrangement of auxiliary apparatuses located around the engine. Similarly, in the latter multi-cylinder engine the port that supplies pressure oil therethrough in a side wall of the engine may restrict the degree of freedom of the auxiliary apparatuses located around the engine.
Moreover, where the latter cylinder cut-off mechanism is applied to a multi-cylinder engine structured such that a cam chain case is disposed transversely across the engine in order to facilitate maintenance and reduce the weight and size of the engine, a working fluid supply port cannot be provided in a side of the engine on which the cam chain case is disposed. Therefore, resulting working fluid supply path is complicated and the cylinder head is obliged to have an increased size and weight.